title: Molecular mobility, composition and structure analysis in glycerol plasticised chitosan films.
abstract: This study was developed with the purpose to investigate the effect of polysaccharide/plasticiser concentration on the microstructure and molecular dynamics of polymeric film systems, using transmission electron microscope imaging (TEM) and nuclear magnetic resonance (NMR) techniques. Experiments were carried out in chitosan/glycerol films prepared with solutions of different composition. The films obtained after drying and equilibration were characterised in terms of composition, thickness and water activity. Results show that glycerol quantities used in film forming solutions were responsible for films composition; while polymer/total plasticiser ratio in the solution determined the thickness (and thus structure) of the films. These results were confirmed by TEM. NMR allowed understanding the films molecular rearrangement. Two different behaviours for the two components analysed, water and glycerol were observed: the first is predominantly moving free in the matrix, while glycerol is mainly bounded to the chitosan chain.
authors.affiliation: CBQF - Centro de Biotecnologia e Química Fina, Escola Superior de Biotecnologia, Centro Regional do Porto da Universidade Católica Portuguesa, Porto, Portugal.
authors.forename: Joana F
authors.initials: JF
authors.lastname: Fundo
authors.forename: Rui
authors.initials: R
authors.lastname: Fernandes
authors.forename: Pedro M
authors.initials: PM
authors.lastname: Almeida
authors.forename: Alexandra
authors.initials: A
authors.lastname: Carvalho
authors.forename: Gabriel
authors.initials: G
authors.lastname: Feio
authors.forename: Cristina L M
authors.initials: CL
authors.lastname: Silva
authors.forename: Mafalda A C
authors.initials: MA
authors.lastname: Quintas
mesh_terms: D048271:Chitosan / Q000737:chemistry*; D018857:Food Packaging / Q000295:instrumentation*; D005990:Glycerol / Q000737:chemistry*; D010968:Plasticizers / Q000737:chemistry*; D014867:Water / Q000032:analysis
chemical_list: D010968:Plasticizers; D014867:Water; D048271:Chitosan; D005990:Glycerol
keywords: Edible films; Microstructure; Molecular dynamics; NMR; Structure–function; Water behaviour